The Caleffi 573403A is a FlowShield DuC-AV dual check backflow preventer with atmospheric vent and a 1/2 in NPT connection, listed to ASSE 1012 for intermediate-hazard protection of potable water lines.
Product data compiled from Caleffi North America technical documentation; warranty per Caleffi North America Limited Warranty. Last reviewed July 2026.
Key Features
ASSE 1012 Intermediate Hazard
Listed to ASSE 1012 for intermediate-hazard potable water protection.
Atmospheric Vent Port
An intermediate atmospheric vent discharges to drain if the upstream check fails, adding a layer of protection over a plain dual check.
Two Serviceable Checks
Two independent inline check valves close automatically under backflow conditions.
Lead-Free Construction
Lead-free brass meeting SDWA Section 1417 and NSF/ANSI/CAN 372; certified to CSA B64.3 and listed by ICC-ES.
Technical Data
| Function | Dual check backflow preventer with atmospheric vent |
|---|---|
| ASSE listing | ASSE 1012 |
| Connection | 1/2 in NPT |
| Body material | Brass EN 12165 CW617N, lead-free per SDWA Section 1417 |
| Maximum operating pressure | 175 psi |
| Medium temperature range | 32 - 210 °F |
| Lead-free compliance | NSF/ANSI/CAN 372 |
Documentation
Technical brochureRelated Products
Frequently Asked Questions
It is a dual check backflow preventer with atmospheric vent for intermediate-hazard potable water protection.
If the upstream check valve fails, the intermediate vent opens to atmosphere and discharges to drain, signaling the fault and adding protection over a plain dual check.
ASSE 1012, and it is lead-free per NSF/ANSI/CAN 372.
This model has a 1/2 in NPT connection.
- Type:
- Dual Check Valve with Atmospheric Vent
- Series:
- FlowShield
- ASSE Standard:
- ASSE 1012
- Connection Type:
- NPT Threaded
- Connection Size:
- 1/2 in
